1. Field of the Invention
The present invention relates to a photographic lens, and more particularly, to a small size photographic lens used in a camera having a image sensing device such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS).
2. Description of the Related Art
Recently, mobile phones having digital cameras using solid state image sensing devices have been widely distributed, the cameras having high image qualities of 3-million pixels or more in view of photographic performance.
Accordingly, a small and light photographic lens that can be fabricated with low fabrication costs is required for such cameras. In addition, in a high-pixel camera module of 3-million pixels or more, a photographic lens optical system that is compact and has an auto-focusing function is required.
Japanese Laid-open Patent No. 2002-365529 and Japanese Laid-open Patent No. 2003-149547 disclose photographic lenses for cameras using solid state image sensing devices.
In Japanese Laid-open Patent No. 2002-365529, the photographic lens arranges an aperture stop on an object side thereof, a first lens having positive refractive power, a second lens having negative refractive power, a third lens having positive refractive power, and a fourth lens having negative refractive power in order of location from the object side.
Japanese Laid-open Patent No. 2003-149547 discloses a photographic lens arranging an aperture stop on an object side thereof, and including a first lens having positive refractive power, a second lens having negative refractive power, a third lens having positive refractive power, and a fourth lens having positive refractive power.
The conventional photographic lens having the above structure has a limitation in providing a compact photographic lens maintaining a high quality imaging for an object positioned a long distance and a short distance away from the lens and having a relatively long back focal length.